Background: Despite national focus on measuring and reducing end-of-life (EOL) systemic treatment among cancer patients, recent studies show a consistently high use of systemic anticancer therapy (SACT) at the EOL, as well as a shift to more targeted therapies. A criticism of measures that focus on deceased populations is that they do not account for patients who received treatment at the same time in their disease trajectory and had a positive response to therapy. We sought to explore whether being treated at an oncologically aggressive (OA) practice (defined as higher practice-level EOL SACT treatment rates), was associated with a survival benefit among patients in six common cancer types. Methods: This survival analysis used the nationwide Flatiron Health electronic health record (EHR)-derived de-identified database. We included all adult patients with a confirmed diagnosis of metastatic disease in breast (mBC), colorectal (mCRC), renal cell carcinoma (mRCC) or pancreatic cancer (mPanc), or advanced disease in non-small cell lung (aNSCLC), or bladder cancer (aUC), between 2015 and 2019. The primary exposures were the practice-level risk-standardized 30-day EOL SACT rates calculated among decedents. The primary outcome was real-world overall survival (rwOS) among all patients. Adjusted hazard ratios (aHR) for each quintile of increasing OA EOL SACT rates (Q2-Q5) were estimated using disease-specific Cox proportional hazard models (reference: Q1), adjusting for patient and practice-level factors. Bonferroni correction was applied to account for multiple comparisons. Results: A total of 78,446 patients from 144 practices were included in the analysis with most patients seen at less OA practices (Q1-Q2). Patients seen at most OA practices (Q5) were less likely to be <65 (32.5% vs 38.9% in Q1), Black (6.3% vs 12.2%), have Medicare (5.9% vs 10.7%) or Medicaid (1.5% vs 4.1%). After adjusting for covariates, there was no statistically significant difference in rwOS between patients treated at the most (Q5) and the least OA practices (Q1; table). However, there was variation among the moderately OA practices. Patients with mPanc seen at moderately OA (Q2-Q4) had 12% to 19% lower hazards of deaths (aHR range 0.81-0.88), compared to those at the least OA practices (Q1), but these associations were not statistically significant (Bonferroni corrected p-values >0.05). Conclusions: When using rates of SACT at EOL to define OA practices, patients treated at these practices do not have improved survival.